An electron-beam drilling apparatus is commonly used for drilling openings in a work-piece, such as a ceramic greensheet. Such greensheets are comprised of ceramic powder formed into sheets and held together with an organic binder contained in a solvent. A typical electron-beam drilling apparatus comprises a chamber which houses the components of the apparatus. A suitable low pressure vacuum is maintained in the chamber, such as by a vacuum pump.
A typical electron-beam drilling apparatus will additionally include an X-Y stage and a beam column for directing the electron beam onto the work piece. The X-Y stage is mounted within the chamber in such a manner that selective two-dimensional movement is possible thus the designation X-Y stage. The stage forms a pedestal including a beam-calibration area and a work-piece area. The beam-calibration area includes sensitive components, such as precision pin holes and faraday cups, which communicate with optical equipment including mirror and interferometer optics also contained within the chamber, which are used in the calibration of the electron beam and positioning of the table for drilling. The work-piece area includes support means designed to support a carrier for the work piece.
The beam column will usually constitute an opening in the chamber through which an electron-beam is projected and focused. In the initial stages of a drilling process, the X-Y stage will be moved into a calibration position whereat the pedestal's calibration area is aligned with the beam column thereby allowing calibration procedures to be performed. These procedures and optical equipment are conventional. The X-Y stage is then moved into a drilling position whereat the pedestal's work-piece area is aligned with the beam column thereby allowing drilling procedures to be performed on a work piece in a conventional manner. The X-Y stage will subsequently move into a variety of drilling positions, each of which, in the work-piece area, is aligned with the beam column to precisely drill an array of holes in the work piece.
Debris is generated during the drilling process which can damage the sensitive components of the apparatus, such as vacuum pumps, optical equipment and/or the bearings mounting the X-Y stages and thus drives for movement. In the past, an electron-beam drilling apparatus was designed to prevent debris from entering the column, however, no features were included to keep debris from entering the rest of the system. Consequently, the chamber needed to be frequently cleaned and the bearings and other components of the X-Y stage were often damaged by debris. Additionally, vacuum pumps had to be provided with special filtering devices to filter out ceramic particles to prevent damage thereto.
Thus there is a need for a debris control-system which contains drilling-generated debris within an easily cleanable area and away from sensitive components.